Symmetric Cryptography 1
summary
Defines two new hardness notions epsilon-one regular hashing and epsilon-two AXU in the ideal cipher model and proves HtE and HtXE maintain full k-bit offline security and ~2^{n/2} online security across u users. Shows CBC-based hash meets the notions, derives bounds for EMAC, XCBC and TMAC, and demonstrates no multi-user degradation versus single-user assumptions. Builds proofs in the ideal cipher model and reports concrete security reductions and query‑bounds.
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chapters (10)
- 0:00Multi-user MAC security intro
- 3:42HtE structure security
- 5:47MAC multi-user challenges
- 8:53Security degradation in multi-user
- 10:42Ideal cipher model proofs
- 12:38New block-cipher hashing notions
- 14:01Security bounds for EMAC/CBC
- 15:30HtXE efficiency improvements
- 17:04Conclusion
- 17:56Q&A
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